By Sara Ganim, Darran Simon and Nicole Chavez

CNN

CLEVELAND, Ohio (CNN) -- A man who allegedly killed an elderly father after he had enjoyed an Easter meal with his children -- then posted a video of the killing on Facebook -- may no longer be in the Cleveland area, police said Monday.

Suspect Steve Stephens, 37, stands charged with Sunday's aggravated murder of 74-year-old Robert Godwin, and authorities say he could be in Pennsylvania, New York, Indiana or Michigan.

Stephens' cell phone last released a "ping," or a signal, in Erie, Pennsylvania, about 100 miles east of Cleveland, police said.

His mother told CNN that when she saw Stephens for the last time on Saturday, he said it would be a miracle if she ever saw him again. They spoke the next day, she said, and he told her he was shooting people because he was angry with his girlfriend.

"He is considered armed and dangerous, so we want people to be careful out there," Cleveland Police Chief Calvin Williams told reporters.

Stephens is a black male who is 6-foot-1 and weighs 244 pounds. He was last seen wearing a dark blue and gray or black striped polo shirt. He was driving a white Ford Fusion with temporary license plates, Cleveland police said.

Police said Sunday night that Stephens "may be out of state at this time," and called on residents in Pennsylvania, New York, Indiana and Michigan to be vigilant.

Horrific footage

The investigation and search for Stephens began Sunday after several people reported an alarming Facebook post, police union president Steve Loomis said

Stephens uploaded a video to his Facebook page showing a gun pointed at a man's head. The gun is fired. The victim recoils and falls to the ground.

The video was posted around 2 p.m. Sunday. Facebook later took it down, calling it prohibited "content."

"We work hard to keep a safe environment on Facebook and are in touch with law enforcement in emergencies when there are direct threats to physical safety," a Facebook spokesperson said in a statement.

Stephens claimed on Facebook that he committed multiple homicides, but police said they have no knowledge of other victims.

As Cleveland police and the FBI were searching for Stephens on Sunday, more than 300 tips poured into the department, police said.

No confirmed sightings of Stephens were reported as the search moved into Monday.

'If you see me again, it'll be a miracle'

Stephens' mother, Maggie Green, told CNN that the oldest of her three children came by her house Saturday afternoon.

"He said this [was] the last time I was going to see him," recalled Green, 53.

Green, a former clerk at the Justice Center Complex in Cleveland who is now on disability, said the conversation confused her.

"If you see me again, it'll be a miracle," she quoted him as saying.

On Sunday, Green learned about the shooting when her youngest son told her about the video.

She was "just dumbfounded" and called Stephens. He told her he was "shooting people" because he was "mad with his girlfriend" of about three years, she said, explaining it was a brief phone call because her phone died.

Asked if she had any message she wanted to relay to her son, she said: "I want him to call me."

Suspect was 'mad' at his girlfriend

Police have not talked about a possible motive in the shooting. Stephens and Godwin didn't know each other, authorities say.

"From what we can tell now, it's just a random person that he picked out. We don't know why," Chief Williams said.

Stephens is employed at Beech Brook, a behavioral health agency in northeastern Ohio that serves children, teenagers and families, according to a spokeswoman for the facility.

"We are shocked and horrified like everyone else," said Nancy Kortemeyer. "To think that one of our employees could do this is awful."

Kortemeyer could not provide Stephens' job title, nor could she say how long he'd worked at Beech Brook. Stephens' mother told CNN he was a social worker.

Victim was 'a good man'

Robert Godwin was walking on the sidewalk when he met Stephens.

He was on his way home from an Easter meal at his children's home when he was killed, CNN affiliate WOIO reported.

"He is a good guy. ... He'd give you the shirt off his back, and I'm not just saying that for these cameras," his son, Robert Godwin Jr. told WOIO.

"This man right here was a good man. I hate he's gone ... I don't know what I'm going to do. ... It's not real."

Sara Ganim reported from Cleveland, Darran Simon reported and wrote from Atlanta, and Nicole Chavez wrote from Atlanta. CNN's Kwegyirba Croffie, Joe Sutton, Chuck Johnston, Amanda Jackson, Christopher Lett, Joel Williams and Shawn Nottingham contributed to this report.